The Fibre Channel port LUN to TARGET device mapping created by Secure Manager is referred to as a Device Map in Command View TL. Secure Manager uses the following rules when creating and modifying a Device Map. Each rule is covered in more depth in the following sections.
1. Devices are ordered based on type and logical position (drive number).
2. Each map will start with LUN 0.
3. New maps remove gaps in the LUN map, but modified maps leave them.
4. If there is more than one FC port on a FC interface controller, then load balancing algorithms are used. a. The first two tape devices are assigned to the first FC port at the next available LUN. The next two
tape devices are assigned to the second FC port at the next available LUN.
b. If there are remaining tape devices, then the next two tape devices are assigned to the first FC port, and the next two to the second FC port. This is repeated until all tape devices are assigned.
5. Maintain FC Port/LUN Map after cabling change on same interface controller.
6. Advanced Secure Manager map creation performs Basic Secure Manager but then removes devices and gaps if necessary.
8. If devices are removed with Advanced Secure Manager any gap made is retained.
9. If devices are removed and added with Advanced Secure Manager, attempts are made to not disturb the other device mappings.
10.Active Fabric is the last LUN on a map of each FC port.
11.If an HBA has access to the robotics for a library partition, the logical robotics device will be added as the next available LUN on the IC physically connected to the robotics.
12.Maps for partitioned libraries still follow the load balancing rules based on the physical drive location.
13.The order each partition is mapped depends on the order that the HBA was added to partitions.
1. Devices are ordered based on type and logical position (drive number)
• Secure Manager uses the drives’ logical position (drive number) as the basis for all mapping operations.
• Robotics are always first in the order of devices therefore they are always assigned LUN 0 in a non-partitioned library.
• Robotics are always assigned to FC Port 0.
• Drives have the next priority. They are ordered based on their logical position (the lower the logical position or drive number, the lower the assigned LUN).
• Active Fabric, if present, will be the last device in a map.
2. Each map will start with LUN 0
LUN maps always start with LUN 0. Therefore the first device in any map will be assigned to 0.
3. New maps remove gaps in the LUN map, but modified maps leave them
New maps are filled without any gaps in the LUN numbering sequence. If a particular host is denied access to a drive, a new LUN map for that host will NOT have an empty placeholder for that drive. Instead the next logical drive will receive the LUN number that would have been used by the inaccessible drive. See Table 10.
Modified maps do leave gaps in the LUN map. If a host previously could see all library devices and then later access was withdrawn for a device, and doing this created a gap in the LUN map, that gap would remain in order to maintain the addresses of the remaining devices in the map. See Table 10.
NOTE: Any changes to device access thereafter will follow the rules for modifying an existing map rather than the rules for creating new maps.
Table 9 Normal device ordering
LUN FC Port 0
0 Robotics
1 Drive 1
2 Drive 2
3 AF
Table 10 New and Modified maps on a 1FC port FC interface controller for a host that cannot access drive 1
NEW MODIFIED
LUN FC Port 0 LUN FC Port 0
0 Robotics 0 Robotics
1 Drive 2 1
The New map did not have access to drive 1 when the map was first created. The Modified map had access to drive 1 when the map was created but was modified to remove access to it.
4. If there is more than one FC port on a FC interface controller, load balancing algorithms are used
Tape devices attached to a particular FC interface controller are sorted in ascending order by logical position in the library. The first two tape devices are assigned to the first FC port at the next available LUNs. The next two tape devices are assigned to the second FC port at the next available LUNs. If there are more than two tape devices per FC port then the following tape devices are assigned in a similar fashion starting over at the first FC port.
Secure Manager takes the following steps when load balancing target devices across FC ports on a dual port FC interface controller (such as an e2400-160):
1. If the robotics controller is attached to the FC interface controller, it is mapped to FC port 0 at LUN 0.
2. The tape devices attached to the FC interface controller are sorted in ascending order by logical position in the library.
3. The first two tape devices are assigned to the first FC port at the next available LUNs.
NOTE: The drives are both assigned to FC Port 0 so that if drives 3 and 4 are added later, the maps will be contiguous.
4. Then next two tape devices are assigned to the second FC port at the next available LUNs.
Table 11 Load balancing with robotics and 4 tape drives on a 2 FC port FC interface controller
LUN FC Port 0 FC Port 1
0 Robotics Drive 3
1 Drive 1 Drive 4
2 Drive 2
Table 12 Load balancing with 2 tape drives on a 2 FC port FC interface controller
LUN FC Port 0 FC Port 1
0 Drive 1
1 Drive 2
Table 13 Load balancing with 3 tape drives on a 2 FC port FC interface controller
LUN FC Port 0 FC Port 1
0 Drive 1 Drive 3
1 Drive 2
Table 14 Load balancing with 4 tape drives on a 2 FC port FC interface controller
LUN FC Port 0 FC Port 1
0 Drive 1 Drive 3
5. If there are remaining tape devices, then the next two tape devices are assigned to the first FC port, the next two to the second FC port. This is repeated until all tape devices are assigned.
The above algorithms are applied to all FC interface controllers in the library.
5. Maintain FC Port/LUN Map after cabling change on same interface controller.
If a device’s cable is moved from one port to another on the same FC interface controller, Secure Manager will attempt to maintain the current FC Port/LUN mapping for the device.
Because devices are mapped by logical position the Interface Manager can correct for devices that have been cabled to different ports on the FC interface controller at power up and FC interface controller reboot. This remapping is not available if the tape device has been moved to a different FC interface controller. The purpose of this feature is to maintain a consistent view of the devices for the hosts connected to the library.
6. Advanced Secure Manager map creation is done like Basic Secure Manager but then removes devices and gaps if necessary
Advanced Secure Manager mapping starts the same way as Basic Secure Manager LUN mapping. Then for each host that can’t see the entire library, devices are removed from the map and any gaps they make will be removed.
The bottom line is that the same rules for creating maps apply to both Basic and Advanced Secure Manager.
• LUN numbers are only assigned to the devices the host can access.
• LUN numbers always start at 0 and are consecutive (no gaps).
Table 15 Load balancing with robotics and 8 tape drives on a 2 FC port FC interface controller
LUN FC Port 0 FC Port 1
0 Robotics Drive 3
1 Drive 1 Drive 4
2 Drive 2 Drive 7
3 Drive 5 Drive 8
NOTE: Any changes to device access thereafter will follow the rules for modifying an existing map rather than the rules for creating new maps.
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7. Maintain current FC Port/LUN assignments when adding devices in Advanced Secure Manager
If an existing map is modified to add a device, previous FC Port/LUN assignments will be retained in an attempt to present a consistent device mapping to the host. The device map is not re-ordered when devices are added.
NOTE: Devices are added to the FC Port that they would have been assigned to using Basic Secure Manager Rules.
Single Fibre Channel Port Example
• Assume Advanced Secure Manager is enabled and that a host has initially been given access to the robotics and drives 2-4:
Table 16 Advanced Secure Manager Mapping Step 1: Maps are created using the same rules as Basic Secure Manager
LUN FC Port 0 FC Port 1
0 Robotics Drive 3
1 Drive 1 Drive 4
2 Drive 2
Table 17 Advanced Secure Manager Mapping Step 2: Devices the host cannot access are removed
LUN FC Port 0 FC Port 1
0 Robotics Drive 3
1 Drive 1 Drive 4
2 Drive 2
Table 18 Advanced Secure Manager Mapping Step 3: Remove gaps in the map
LUN FC Port 0 FC Port 1
0 Drive 1 Drive 3
1 Drive 2
2
Table 19 Map for host with access to robotics and drives 2-4
LUN FC Port 0
0 Robotics
1 Drive 2
2 Drive 3
• If the library administrator later grants the host access to Drive 1, the current FC Port/LUN mappings will be retained and the new Device Map will look like:
8. If modifying an existing map to remove device access with Advanced Secure Manager any gap made is retained
If Advanced Secure Manager is used to remove access to a device for a host with a preexisting map, any gap this change makes will be maintained.
Some operating systems have issues with non-contiguous LUN maps. Therefore it is recommended to avoid gaps in the LUN map if at all possible.
There are three methods of removing the gap(s) created by this process.
1. All hosts using this map need to be removed and re-added and a new map needs to be created.
2. Changing the Mode from Automatic to Manual and back to Automatic will clear out all customizations (not recommended unless the number of customizations is low).
3. Add access to a device connected to that FC interface controller and that would normally be mapped to that FC port and it will fill the first gap in the LUN order.
NOTE: Options 1 and 2 require the backup software to reconfigure the library. Option 3 should only require reconfiguring the software for the new device.
9. If devices are removed and added with Advanced Secure Manager, attempts are made to not disturb the other device mappings
If host access is changing to add and remove devices, efforts are made to not disturb the devices. If possible, the newly added device will fill the gap made by the removed device. This is done to retain the LUN assignments of the other devices. A device will only be added back to the FC port that it would have been assigned to in Basic Secure manager (i.e. Robotics and drives 1 and 2 will always be on FC port 0.
Table 20 Map for host given access to drive 1 after robotics and drives 2-4 were mapped
LUN FC Port 0 0 Robotics 1 Drive 2 2 Drive 3 3 Drive 4 4 Drive 1
Table 21 1 FC port Advance Secure Manager Device Access Removal: Removing device
LUN FC Port 0
0 Robotics
1 Drive 1
2 Drive 2
Table 22 1 FC port Advance Secure Manager Device Access Removal: End result
LUN FC Port 0
0
1 Drive 1
NOTE: When devices need to be removed and added, it is recommended to remove devices first and then add new devices second, to prevent or lessen the chance of creating gaps in LUN maps, which may create problems in some operating systems.
Example
A host has access to the robotics and drives 2, and 4.
Advanced Secure manager is used to remove access to the robotics.
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10. Active Fabric is the last LUN on a map of each FC port
One Active Fabric (AF) controller LUN is included as the last LUN in each FC port map that has a drive with a Direct Backup (X-Copy) license. Active Fabric is used by L&TT to communicate with the FC interface controllers and by some software for X-Copy/Direct Backup (a licensed functionality) implementation.
Table 23 Advance Secure Manager Device Access Change Step 1 (1FC Port): Remove devices
LUN FC Port 0
0 Robotics
1 Drive 1
2 Drive 2
Table 24 Advance Secure Manager Device Access Change Step 2 (1 FC Port): Add devices to fill gaps if possible
LUN FC Port 0
0 Drive 3
1 Drive 1
2 Drive 2
Table 25 Map from 2 FC port IC with access to the robotics, and drives 2 and 4
LUN FC Port 0 FC Port 1
0 Robotics Drive 4
1 Drive 2
Table 26 Robotics access is removed
LUN FC Port 0 FC Port 1
0 Robotics Drive 4
1 Drive 2
Table 27 Access to drive 3 is added
LUN FC Port 0 FC Port 1
0 Drive 4
IMPORTANT: Active Fabric is NOT displayed in Secure Manager. Active Fabric does not conform to the rules that other devices are governed by. It will always be the last LUN in the map for each FC port. If another device is added to the end of the list it will take the LUN currently occupied by AF and AF will take the LUN after the device. If the last device is removed, then AF will move to fill in the gap.
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Example
AF mapping when access to a device is added.
Example
AF mapping when access to a device is removed.
Table 28 Map of 4 drive library on a 2 FC port IC with Direct Backup enabled on Drive 3 or 4 and AF visible
LUN FC Port 0 FC Port 1
0 Robotics Drive 3
1 Drive 1 Drive 4
2 Drive 2 AF
Table 29 LUN map where access to drive 2 is not granted and Direct Backup is enabled for drive 1
LUN FC Port 0
0 Robotics
1 Drive 1
2 AF
Table 30 AF LUN map placement after adding drive 2
LUN FC Port 0
0 Robotics
1 Drive 1
2 Drive 2
3 AF
Table 31 LUN map where access to drive 2 is being removed and direct backup is enabled for drive 1
LUN FC Port 0
0 Robotics
1 Drive 1
2 Drive 2
11. If an HBA has access to the robotics for a library partition, the logical robotics device will be added as the next available LUN on the IC physically connected to robotics
Each partition of a partitioned library will have its own logical robotics device. This device will be mapped to the FC port 0 of the IC that is physically connected to the robotics. The logical robotics device will be first in order of devices for that partition but it will not have any priority over devices that have already been mapped to a particular HBA. In other words, it will have the highest priority in the new devices added to the map but it will not displace any device previously added to the map.
NOTE: When partitioning is in use, only logical (or virtual) robotics devices will be mapped. The physical (or actual) robotics device will not appear in any LUN map.
Partition 1 has drives 1 and 2. Partition 2 has drives 3 and 4. All drives and robotics are connected to a 1 host port IC, and the HBA was given access to Partition 1 first.
The IC physically connected to the robotics has only one host port and is not connected to any drives.
NOTE: If a host has access to the robotics and drives for many partitions of a partitioned library then the map for the IC connected to the robotics could exceed 8 LUNs. If this occurs, then ensure that the HBA, OS, drive, and software have support for more than 8 LUNs.
Table 32 AF map placement after drive 2 is removed
LUN FC Port 0
0 Robotics
1 Drive 1
2 AF
Table 33 A map for an HBA with access to the robotics and drives for Partition 1 and Partition 2
LUN FC Port 0
0 Robotics (Partition 1) 1 Physical Drive 1 (Partition 1, Drive 1) 2 Physical Drive 2 (Partition 1, Drive 1) 3 Robotics (Partition 2) 4 Physical Drive 3 (Partition 2, Drive 1) 5 Physical Drive 4 (Partition 2, Drive 2)
Table 34 A map for an HBA with access to the robotics on two partitions
LUN FC Port 0
0 Robotics (Partition 1) 1 Robotics (Partition 2)
12. Maps for partitioned libraries still follow the load balancing rules based on the physical drive location
The load balancing algorithms used to distribute traffic between FC Port 0 and FC Port 1 still use the same rules as non-partitioned libraries and are based on the physical instead of the logical partition drive numbering.
Partition 1 has physical drives 1 and 2. Partition 2 has physical drives 3 and 4. All drives are connected to a 2 FC port IC, and the HBA was given access to Partition 1 first.
Partition 2 has physical drives 3 and 4. Physical drives 3 and 4 are connected to a 2 host FC port IC. The physical robotics is connected to a different IC not represented in Table 36.
13. The order each partition is mapped depends on the order that the HBA was added to partitions
Because the mapping occurs when each HBA is added to a partition, the order that an HBA is added to partitions will govern the order in which each partition’s devices show up in the maps for that HBA. For this reason, it is recommended that each HBA be added to partitions in order starting with partitions
containing the lowest numbered physical drives and ending with the highest numbered physical drives.
Example
An HBA is added to Partition 1 and then Partition 2. Partition 1 contains physical drive 1. Partition 2 contains physical drive 2. The robotics, drive 1 and drive 2 are all connected to an IC with one host port.
Table 35 A map for an HBA with access to the drives for Partition 1 and Partition 2
LUN FC Port 0 FC Port 1
0 Physical Drive 1 (Partition 1, Drive 1) Physical Drive 3 (Partition 2, Drive 1) 1 Physical Drive 2 (Partition 1, Drive 2) Physical Drive 4 (Partition 2, Drive 2)
Table 36 A map for an HBA with only access to Partition 2
LUN FC Port 0 FC Port 1
0 — Physical Drive 3 (Partition 2, Drive 1)
1 — Physical Drive 4 (Partition 2, Drive 2)
Table 37 The HBA is granted access to Partition 1
LUN FC Port 0
0 Robotics (Partition 1) 1 Physical Drive 1(Partition 1, Drive 1)
Table 38 The HBA is then granted access to Partition 2
LUN FC Port 0
0 Robotics (Partition 1) 1 Physical Drive 1 (Partition 1, Drive 1) 2 Robotics (Partition 2) 3 Physical Drive 2 (Partition 2, Drive 1)
Example
An HBA is added to Partition 2 and then Partition 1. Partition 1 contains physical drive 1. Partition 2 contains physical drive 2. The robotics, drive 1 and drive 2 are all connected to an IC with one host port.